#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define ld  long double

using LL = long long; using ULL = unsigned long long;
using VI = vector<int>; using VVI = vector<VI>; using VVVI = vector<VVI>;
using VL = vector<LL>; using VVL = vector<VL>; using VVVL = vector<VVL>;
using VB = vector<bool>; using VVB = vector<VB>; using VVVB = vector<VVB>;
using VD = vector<double>; using VVD = vector<VD>; using VVVD = vector<VVD>;
using VC = vector<char>; using VS = vector<string>; using VVC = vector<VC>;
using PII = pair<int,int>; using PLL = pair<LL,LL>; using PDD = pair<double,double>; using PIL = pair<int,LL>;
using MII = map<int,int>; using MLL = map<LL,LL>;
using SI = set<int>; using SL = set<LL>;
using MSI = multiset<int>; using MSL = multiset<LL>;
template<class T> using MAXPQ = priority_queue<T>;
template<class T> using MINPQ = priority_queue< T, vector<T>, greater<T> >;

const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1LL << 60;
#define PI  3.14159265358979323846

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define EACH(e, v) for(auto &e : v)
#define RITR(it, v) for(auto it = (v).rbegin(); it != (v).rend(); ++it)
#define ALL(v) v.begin(),v.end()

vector<ll> x8={1,1,1,0,0,-1,-1,-1},y8={1,0,-1,1,-1,1,0,-1};
int dx4[4]={1,-1,0,0}, dy4[4]={0,0,1,-1};

/*
memo
-uf,RMQ(segtree),BIT,BIT2,SegTree,SegTreeLazy
-isprime,Eratosthenes,gcdlcm,factorize,divisors,modpow,moddiv
nCr(+modnCr,inverse,extend_euclid.powmod),tobaseB,tobase10
-dijkstra,Floyd,bellmanford,sccd,topological,treediamiter
-compress1,compress2,rotate90

-co,ci,fo1,fo2,fo3,fo4
-bitsearch,binaryserach
-bfs
-SegTreedec,SegTreeLazydec
*/

//要素数Nの有向グラフGの頂点に順序をつける
template<class T>
VL topological_sort(const VVL &G, T N){
    VL indeg(N, 0);
    for(ll i = 0; i < N; i++){
        for(auto c : G[i]){
            indeg[c]++;
        }
    }

    priority_queue<T, VL, greater<T>> heap;
    for(ll i = 0; i < N; i++){
        if(indeg[i] == 0) heap.push(i);
    }

    VL ans;
    while(!heap.empty()){
        int state = heap.top();
        heap.pop();
        ans.push_back(state);
        for(auto next : G[state]){
            indeg[next]--;
            if(indeg[next] == 0) heap.push(next);
        }
    }

    return ans;
}

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    ll N; cin >> N;
    VL s(N); for(ll i = 0; i < N; i++) cin >> s[i];
    VVL G(N);
    for(ll i = 0; i < N-1; i++){
        ll a,b; cin >> a >> b;
        a--,b--;
        if(s[a] < s[b]) G[a].push_back(b);
        if(s[a] > s[b]) G[b].push_back(a); 
    }

    VL id = topological_sort(G,N);

    VL dp(N,0);
    for(ll i = 0; i < N; i++){
        ll from = id[i];
        for(auto to : G[from]){
            dp[to] = max(dp[to],dp[from]+s[from]);
        }
    }

    ll ans = 0;
    for(ll i = 0; i < N; i++) ans = max(ans,dp[i]+s[i]);
    cout << ans << '\n';
    
    
}